Image receiving materials with whitening agents for a silver salt diffusion transfer process and method of preparing the same

ABSTRACT

Image receiving materials for a silver salt diffusion transfer process which comprise a support and at least two layers superposed on the surface of the support comprising a cellulose ester layer and a hydrolyzed cellulose ester layer. The former cellulose ester layer contains at least one fluorescent whitening agent and the latter hydrolyzed cellulose ester layer contains silver depositing nuclei. The method of preparing the same is also disclosed.

titted States Patent 1 1 3,873,317 Kato et al. Mar. 25, 1975 [54] IMAGE RECEIVING MATERIALSWITH 3,607,269 9/l97l Young 96/76 R WHITENING AGENTS FOR A SILVER SALT E 1 a 0 e a DIFFUSION TRANSFER PROCESS AND 3,791,845 2/1974 Tuite 96/82 METHOD OF PREPARING THE SAME Inventors: Kazunobu Kato; Kinji Ohkubo, both of Ashigara, Kanagawa, Japan Assignee: Fuji Photo Film Co., Ltd., Ashigara- .sllit ien s Japan Filed: May 11, 1973 Appl. No.: 359,382

Foreign Application Priority Data May 11, 1972 Japan 47-46730 US. Cl. 96/76 R, 96/82 llnt. Cl G030 1/48, GO3c 1/ 92 Field of Search 96/76 R, 82

References Cited UNITED STATES PATENTS 12/1969 Pattijn et al. 96/82 Primary ExamirierNorman G. Torchin Assistant Examiner-Richard L. Schilling Attorney, Agent, or FirmSughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Image receiving materials for a silver salt diffusion transfer process which comprise a support and at least two layers superposed on the surface of the support comprising a cellulose ester layer and a hydrolyzed cellulose ester layer. The former cellulose ester layer contains at least one fluorescent whitening agent and the latter hydrolyzed cellulose ester layer contains silver depositing nuclei. The method of preparing the same is also disclosed.

21 Claims, No Drawings IMAGE RECEIVING MATERIALS WITH WHITENING AGENTS FOR A SILVER SALT DIFFUSION TRANSFER PROCESS AND METHOD OF PREPARING THE SAME BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image receiving materials for a silver salt diffusion transfer process and to a method of preparing the same, more precisely, to those which consist of a support and at least two layers comprising a cellulose ester layer which contains at least one fluorescent whitening agent and a hydrolyzed cellulose ester layer which contains silver depositing nuclei, the two layers being superposed on the surface of the support.

2. Description of the Prior Art Diffusion transfer photographic processes are known which use a silver salt such as a silver halide. In such processes a photographic light-sensitive element prepared by applying a dispersion wherein fine particles of a light-sensitive silver salt such as a silver halide are dispersed into a hydrophilic binder such as gelatin, polyvinyl alcohol, carboxymethyl cellusose, polyvinyl pyrrolidone, methyl cellulose, etc., on a support such as paper, baryta paper or a high molecular weight substance film, e.g., polyethylene terephthalate, cellulose diacetate, cellulose triacetate, cellulose nitrate, polycarbonate, polyvinyl chloride, etc., is exposed to form an image in the light-sensitive layer thereof, and the thus exposed element is developed by contacting the same with a treating solution containing a developer.

In this development, the exposed silver halide in the light-sensitive layer is reduced (or developed) to form non-diffusible silver deposits. At the same time or subsequently, when the light-sensitive element is contacted with a water soluble silver complex forming agent, the silver halide which has not been exposed is reacted with the complex forming agent to form a water soluble silver complex compound. When an image receiving element which consists of a layer (an image receiving layer) containing a dispersion of a substance which is a catalyst for the reduction of the water soluble silver complex compound (silver depositing nuclei, that is, so-called physical development nuclei) in a hydrophilic binder is closely contacted with the light-sensitive layer, the silver complex compound formed in the lightsensitive layer is diffused, by the action of a treating solution, and transferred from the light-sensitive layer to the image receiving layer, and reduced to silver deposits in the image receiving layer by the action of the development nuclei.

When these phenomena are observed from the view of the whole surface of the image receiving layer, a silver image is formed as if the image was transferred to the image receiving layer from the light-sensitive layer. This photographic process is thus appropriately called a silver salt diffusion transfer photographic process.

Various studies have hitherto been made on silver salt diffusion transfer materials, e.g., on the image receiving materials used in the process. For example, as

the silver depositing nuclei there are used, in general,

metal sulfides or metal selenides which are at most only slightly soluble in water, or colloidal heavy metals or noble metals. It is desirable, however, that the silver depositing nuclei in the image receiving materials have a high activity.

In view of such requirements, U.S. Pat. No. 2,698,237 teaches a process for making silver depositing nucleihaving a high activity by mixing a water soluble metal salt and a water soluble sulfide in fine particles of silicon dioxide to form precipitates of a water insoluble metal sulfide. Further, Japanese Pat. Publication No. 32754/69 describes image receiving materials which can be prepared by the following steps: after a silver depositing nuclei substance has been incorporated into an alkali impermeable polymer substance by means of a vacuum evaporation coating method, the thus treated substance is dissolved in a solvent for the polymer substance and the resulting solution is applied onto a support and dried, and then the surface of the polymer layer is subjected to a chemical treatment, such as hydrolysis, to make the surface permeable to an alkaline substance.

In our co-pending Japanese Pat. Application No. 91240/71 there is described a process for producing image receiving materials for a silver salt diffusion transfer process wherein a cellulose ester layer free of silver depositing nuclei is provided on a paper support, the surface layer of the cellulose ester layer is hydrolyzed and silver depositing nuclei are included in the hydrolyzed layer.

In these image receiving materials, it is preferred to incorporate one or more fluorescent whitening agents in the cellulose ester layer to improve the whiteness of the support.

However, when a cellulose ester layer containing a fluorescent whitening agent(s) is subjected to hydrolysis treatment, the following defects occur: when a support as above is immersed in a solution for hydrolysis (in general, a methanolic aqueous solution containing an alkaline substance) to hydrolyze a part of the cellulose ester layer, the fluorescent whitening agents contained in the hydrolyzed layer are extracted out into the hydrolysis solution. As a result, when the hydrolysis is continuously performed, the extracted fluorescent whitening agent(s) accumulate in the solution for the hydrolysis, whereby sludge precipitates therein, or the accumulated fluorescent whitening agent(s) is redeposited on the surface of the support, which interferes with the whiteness of the support, that is, the whiteness becomes uneven due to the redeposition.

In addition, the whiteness of the support before the hydrolysis differs from that of the support after hydrolysis, and so it becomes difficult to control the whiteness of the support in the preparation thereof.

SUMMARY OF THE INVENTION After efforts to eliminate the above mentioned defects, we reached the image receiving materials of this invention, i.e., image receiving materials for a silver salt diffusion transfer process which comprise a support and at least two layers, one comprising a cellulose ester layer which contains at least one fluorescent whitening agent and the other comprising a hydrolyzed cellulose ester layer which contains silver depositing nuclei, the two layers being superposed on the surface of the support.

These image receiving materials can be prepared by the following steps: After a cellulose ester layer containing one or more fluorescent whitening agents is applied to a support, another cellulose ester layer free of fluorescent whitening agents is superposed thereon to form a laminated support, and then the surface layer of the laminate support is hydrolyzed and silver depositing nuclei are incorporated and deposited in the hydrolyzed layer.

When the layer containing fluorescent whitening agent(s) and the other layer free of fluorescent whitening agents are separately applied to the support, a part of the fluorescent whitening agents may diffuse, in general, from the layer containing the same to the layer free of the same. So long as the amount of the diffused fluorescent whitening agents is not such that the amount of the agents extracted out into the solution for hydrolysis is harmful or is such as to lower the fluorescent brightening effect, whereby unacceptable results would occur, such an embodiment is, of course, included in the scope of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Since the support used in the image receiving materials of the present invention serves the well known supporting function of such materials known to the art, the support is not limited with respect to the kind (such as the quality), thickness or exact properties thereof as well as the manufacturing method thereof, and the support may be freely chosen from those known in the art. Particularly, preferred are photographic base paper, pigment (such as baryta, titanium white or the like) coated paper, polyethylene coated paper or a film made of high molecular weight substance such as polyethylene terephthalate, cellulose acetate, cellulose nitrate, polycarbonate, polyvinyl chloride, etc., artificial papers and the like.

With respect to the cellulose ester layer provided on the paper support and the cellulose ester layer provided thereover, this can be accomplished as follows: one or more cellulose esters is/are dissolved in a solvent therefor and the solution applied on the support, e.g., paper and dried; alternatively, a cellulose ester film is adhered to the support, e.g., paper, by means of heat/- pressure fusion or by an adhesive.

Examples of typically used solvents include esters such as methyl acetate, ethyl, etc., ketones such as acetone, diacetone alcohol polyhydric alcohols such as methyl cellosolve, ethyl cellosolve, etc. Typical heat/- pressure fusion formation conditions are at 60 80 C and 4 8 kglcm Typical adhesives are polyvinyl acetate resin, polyester resins, polyisocyanate resins, and the like.

Any process used should insure firm bonding, and so long as firm bonding is obtained, the process is not particularly limited.

Representative of the cellulose esters are, for example, organic acid cellulose esters such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, etc., inorganic acid cellulose esters such as cellulose nitrate, etc., and mixtures thereof.

The thickness of the hydrolyzed cellulose ester layer containing silver depositing nuclei is preferably about 0.1 to about 20 t particularly 0.5 to 10 [L so that an image having excellent image quality can be obtained.

The thickness of the cellulose ester layer containing one or more fluorescent whitening agent(s) is preferably about 0.5 to about M, particularly l-lO p., so that the layer can act as a water-proofing layer against the permeation of developing treatment solution, and that a sufficient whitening effect can be attained.

Accordingly, in order to prepare an image receiving material having the above mentioned thicknesses, respectively, a cellulose ester layer containing fluorescent whitening agent(s) is firstly applied to support in a thickness of about 0.5 to about 20 u, preferably l-lO .L, and then another cellulose ester layer is superposed on the thus coated support in a thickness to correspond to that of the desired hydrolyzed layer.

The thickness of the hydrolyzed layer may be controlled to any optional thickness of about 0.1 to about 10 a by controlling the alkali concentration or alcohol concentration of the solution for hydrolysis or the period for the hydrolysis treatment as well as the temperature of the solution for hydrolysis. For example, more alkali or more alcohol (e.g., 3O 50%) and longer times or higher temperatures increase hydrolysis.

If the thickness of the image receiving layer is too low, it becomes difficult to obtain a sufficient transfer concentration. On the contrary, if the thickness is too great, a large amount of treating solution penetrates into the interior of the layer, and as a result, unfavorable results can occur, such as the image receiving sheet will be stained due to the oxidation of developer or the storage stability of the formed silver image is reduced.

It is to be understood, of course, that the present invention includes the following embodiment: hydrolyzed/silver depositing nuclei layer; unhydrolyzed layer free of brightening agent; unhydrolyzed layer containing brightening agent.

If necessary, an acid substance layer to neutralize the alkaline components in the solution for development treating, etc., may be provided between the cellulose ester layer containing fluorescent whitening agent(s) and the hydrolyzed cellulose ester layer containing silver depositing nuclei. Simply stated, any layer that contains an acid compound will do as the acid substance layer. Especially preferred are the polymer acids, e.g., homopolymers or copolymers of maleic anhydride and phthalic acid.

As the fluorescent whitening agents to be used in the present invention, various kinds of commercially available fluorescent whitening agents can be utilized, and these agents are not particularly limited with respect to the kinds thereof, though preferably they are soluble in solvents for cellulose esters. Of coure, other fluorescent whitening agents which are insoluble in solvents for cellulose esters may also be used, and these are added in the form of a dispersion.

Representatives of the fluorescent whitening agents are mentioned hereunder, The following are described in Color Index Vol. 2 (2nd Ed., 1956, The Society of Dyers and Colorists).

C.I. Fluorescent Brightening Agent 4 Calcofluor Yellow HEB (American Cyanamid Co.,) do do. 57

Fluorescent Brightening Agent 128 Hiltamine Arcttiie White DML (Hil3t8n David Chemical Co.)

o. Calcofluor White LD (American Cyanamid Co.,)

Other fluorescent whitening agents which are not described in this Color Index may also be used. These are commercially available and as follows:

Whitelluor PHR Sumitomo Kagaku Kogyo KK Whitefluor B Sumitomo Kagaku Kogyo KK Uvitex OB Ciba Ltd.

Kayalight A Nippon Kayaku KK do. B do.

Kaycoll C Nisso Kako KK do. E do.

Blankophor DCB Bayer do, KZOUSK 0,

It is preferred to incorporate one or more of these fluorescent whitening agents in an amount of about 5 to about 500 mg/m particularly -200 mg/m of the layer containing the same. If the amount added is too small a sufficient whitening effect cannot be attained. On the other hand, if too much is added, the yellowbrown color of the fluorescent whitening agents themselves appears. The appropriate amount of the fluorescent whitening agent(s) to be added varies, depending upon the kind(s) thereof used, and it is necessary to select the most effective and optimum amount of the respective fluorescent whitening agents to be added on a case by case basis, considering the above two factors.

In addition, fluorescent whitening agents which are described in the following patent publications may also be used in the present invention.

Japanese Pat. Publication Nos. 6442/65, 7709/66, 6616/65, 11338/67, 21016/67, 26185/67, 20456/67, 25336/68, 9928/68, 21220/69, 12035/69, 37194/70,

22557/69, 38986/70, 823/71, 3829/71, 822/71, 34939/70, 8782/71, 8784/71, 15152/71, 6515/71, 40552/71, 19714/71, 30586/71, 23518/71 and 28995/71', US. Pat. Nos. 3,575,996, 3,586,673,

heavy metals such as zinc, mercury, lead, cadmium,- iron, chromium, nickel, tin, cobalt, copper, etc., noble metals such as palladium, platinum, silver, gold, etc., or sulfides, selenides, tellurides, etc. of these metals. These silver depositing nuclei substances are obtained, for example, by reducing the corresponding metal ion in an aqueous solution of a water soluble polymer (which is called a protective colloid) such as gelatin, polyvinyl alcohol, carboxymethyl cellulose, methyl cellulose, etc., to form a colloidal metal dispersion, or by mixing a metal ion solution with a solution of a soluble sulfide, selenide or telluride to form a colloidal dispersion of a water insoluble metal sulfide, metal selenide or metal telluride.

Various methods can be used for the hydrolysis of the surface of the cellulose ester layer and the incorporation of silver depositing nuclei, and some embodiments thereof will be described hereunder.

Method 1. A cellulose ester layer is immersed in a hydrolyzing solution bath or the solution is applied to the surface of the layer, whereby the said solution reacts with the ester, and after the surface layer of the cellulose ester layer is hydrolyzed, the layer is immersed in a dispersion containing silver depositing nuclei or the dispersion is applied to the surface of the layer, whereby the silver depositing nuclei are incorporated in the hydrolyzed layer;

Method 2. By treating the surface of a cellulose ester layer with a hydrolyzing bath containing silver depositing nuclei, the surface layer of the cellulose ester layer is hydrolyzed and at the same time the silver depositing nuclei are incorporated in the hydrolyzed layer. In this method, the hydrolysis of cellulose ester layer and the incorporation of silver depositing nuclei are simultaneously performed in one bath.

Method 2 is more advantageous than Method 1 in that the silver depositing nuclei can be uniformly penetrated into the cellulose ester layer. In particular, when a metal sulfide is used as the silver depositing nuclei, Method 2 is more preferred, since metal sulfides are stable in an alkaline oxidizing bath and the hydrolysis treatment and the application of the silver depositing nuclei can be performed at the same time.

However. when the silver depositing nuclei have been obtained as a colloidal dispersion, other specific methods in addition to Method 1 and Method 2 are required. This is because silver depositing nuclei formed in a protective colloid polymer are stably protected therein, and thus are penetrated only with difficultly into the hydrolyzed layer. These methods are as follows:

The hydrolysis conditions are not particularly limited, but excellent products are obtained following the guidelines described below: alkali (preferably an alkali metal hydroxide) about 1 to about 30% (weight solvent (an alcohol preferably methanol and/or ethanol) aboutlflto about 60%, and H 0 (correspondingly about to about 40% (weight); glycerin about 10 to aisou'tse' 1; 5a; cc H O; silver depositing nuclei (a) heavy metal or noble metal 0.001 0.1 g/llhydrolyzing sol; (b) soluble sulfide, l300 X the chemical equivalent to (a). The same basic conditions are used in all of methods 1 4.

Method 3. A water soluble metal salt and a water soluble sulfide, selenide, telluride or sulfur containing compound (preferably an organic sulfur containing compound) are dissolved in a solvent containing glycerin or a glycerin derivative to form a water soluble.

metal sulfide, selenide or telluride.

Method 4. A water soluble metal salt and a reducing agent are mixed in a solvent containing glycerin or a glycerin derivative to form a colloid.

Typical metals used in the above processes are zinc, cadmium, lead, iron, nickel, cobalt and tin, in the form of a water soluble metal salt, such as an acetate, nitrate, borate, chlorate, sulfate, hydroxide, formate, citrate etc..

Typical of the sulfides, selenides tellurides or (organic) sulfur compounds are the sulfides of alkali metals (such as sodium, potassium), ammonium sulfide, ammonium, poly-sulfide, etc., tellurium compounds and selenium compounds of alkali metals and the like;

thiourea, urea, potassium thiocyanate, thioacetoamide, sodium thiosulfate, and the like, are also profitably used. Any reducing agent which reduces the components in Method 4 can be used, with dextrin, sodium borohydride, hydroxylamine and hydrazine being good because of lowered pollution problems.

The hydrolysis conditions are essentially the same as heretofore defined for the case of general hydrolysis.

The temperature and time of any of the above hydrolysis methods is not overly critical, and generally speaking the cellulose ester material is merely contacted with the hydrolyzing both at ambient conditions for a few minutes sufficient to achieve the desired depth of hydrolysis. Most excellent results are obtaine however, when the hydrolyzing bath is contacted (immersion, spraying, etc.), with the cellulose ester layer for from about seconds to lOO sec. at a bath temperature of from about 20 to about 50 F, more conservatively from to F. Little is to be gained at subor superatmospheric pressures, though such can be used.

The glycerin or the glycerin derivative in the above mentioned Method 3 or Method 4 is efficient for introducing the silver depositing nuclei into the hydrolyzed cellulose ester layer. It also is possible to add another step, i.e., after the silver depositing nuclei are formed in a liquid other than the glycerin or glycerin derivative, such as water or a polymer in the form of a fluid (e.g., liquid polymer or polymer solution), or the like, the glycerin or the glycerin derivative is added in the liquid.

In general, silver depositing nuclei substances have the defect that they are easily oxidized. The use of glycerin and the like is effective for the preservation of the silver depositing nuclei substances for a long period of time in that the glycerin and the like have an antioxidizing property. Further, glycerin and the like are a preferred medium for the dispersion of fine nuclei substance colloids, and thus are effective for maintaining the said colloids in the state of stable, fine particles. When the nuclei dispersion colloid is formed in glycerin, nuclei substances which are very fine and highly active may be obtained. This is a very favorable merit.

Representatives of the glycerins and glycerin derivatives are, for example, polyglycerin aotc a atewea oina (T name: Polwerin,

manufacture; Nippon Yushi KK, this includes two grades, one having a molecular weight of 1,300 and the other a molecular weight of 2,000.), diglycerin, organic acid esters of glycerin and polyglycerin (such as glycerol monoacetate, glycerol diacetate, glycerol triacetate, glycerol monooleate, glycerol monolaurate, glycerol monostearate, the monostearic acid ester of polyglycerin, the monolauric acid ester of polyglycerin), so-

dium glycerophosphate, potassium glycerophosphate, etc.

In the above mentioned Method 3 and Method 4, the thus prepared glycerin solution wherein silver depositing nuclei are dispersed and the above mentioned alcohol aqueous solution containing an alkaline agent are admixed together.

According to the various methods mentioned above, a cellulose ester layer whose surface has been hydrolyzed and which contains silver depositing nuclei may be formed on a support such as, e.g., paper. After the layer has been formed, the same may, if necessary, be washed with water, or, if excess alkaline substance contained in the alkali solution which was used in the hydrolysis has been neutralized with an aqueous solution of an acid, the layer may then be washed with water and dried.

The image receiving material thus prepared and a silver halide photo-sensitive material which has been imagewise exposed are superposed so that the image receiving layer and the exposed layer are contacted in face to face relationship, a treating solution is introduced between the two layers, and then after these two layers are closely contacted for a certain determined period as such, the image receiving material and the negative material are separated, whereby on the image receiving layer of the image receiving material a positive silver image is formed. 7

The above mentioned treating solution usually includes a thickener which provides a highly viscous solution, for example, cellulose derivatives such as carboxymethyl cellulose, ethyl cellulose, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, etc., vinyl polymers such as polyvinyl alcohol, etc., acrylic acid polymers such as polymethacrylic acid, polyacrylic acid, etc., inorganic polymers such as water glass, etc.; an inorganic silver complex forming agent such as a thiosulfate (for example, sodium-, potassiumor ammonium thiosulfate), thiocyanate (for example, sodium-. potassiumor ammonium thiocyanate), etc; an organic cyclic imide such as uracil, barbituric acid, urasol, hydantoin, etc. (refer to US. Pat. No. 2,857,274) or a basic nitrogen containing compound such as ethylamine, ethanolamine, etc. (refer to US. Pat. No. 3,343,958); a developer such as hydroquinone, a hydroquinone derivative (for example, toluhydroquinone, t-butyl-hydroquinone, phenylhydroquinone, etc.), p-aminophenol, a p-aminophenol derivative (for example, N-methyl-p-aminophenol,

trimethyl-p-aminophenol, etc.), hydroxylamine, a hydroxylamine derivative (for example, N-dimethoxyethyl-hydroxylamine, N-diethoxyethyl-hydroxylamine, diethyl-hydroxylamine, etc.), a3-pyrazolidone, a 3- pyrazolidone derivative (for example, l-phenyl-3- pyrazolidone, etc.), ascorbic acid, etc.; and an alkaline agent such as an inorganic alkali, for example, sodium carbonate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, etc., or an amine for example, ethanolamine, diethanol amine, etc. In some cases, a part or all of the silver halide solvent, thickener, developer and alkaline agent may be incorporated in the silver halide light-sensitive element or in the image receiving element.

It is preferred to make the treating solution highly viscous, particularly when the image receiving material is adapted for use in a so-called Polaroid-Land type camera wherein a treating means for development is incorporated. This is because if the treating solution is highly viscous, the amount thereof used can be small, the total amount thereof can efficiently be used. Further, the treating solution can be kept in a predetermined position due to the high viscosity thereof. in the developing treatment, the solution can easily be spread between the silver halide light-sensitive element and the image receiving element without loss of any solution. Thus, various merits result from the use of such a highly viscous treating solution. When the lightsensitive element and the image receiving element are separated after the development, it is preferred to make the surface of the image receiving element smooth, or to provide a thin separation improving layer such as gum arabic, hydroxyethyl-cellulose, cellulose acetate phthalate, etc., on the image receiving layer in order that the highly viscous treating solution does not remain on or adhere to the image receiving element.

The silver halide light-sensitive layer contains one or more silver halides such as silver chloride, silver bromide, silver iodide, silver chlorobromide, silver iodobromide or silver chloroiodobromide, but for use as a photographic material for taking a picture, silver bromide and silver iodobromide emulsions are preferred. Those silver halides with an average grain size of 0.1 ,u. 10 ,u provide best results. Light sensitizers, chemical sensitizers, antifoggants, gelatin hardeners and surface active agents can be added as desired to serve their art recognized functions. These silver halides are dispersed in a protective colloid substance such as a natural polymer, for example, gelatin, colloidion, agar agar, etc. or a synthetic polymer, for example polyvinyl alcohol.

Such elements are described in detail in P.Glafkides, Chimie et Physique Photographique," (3rd ed., Publication Phot-Cinema Paul Montel [967).

In those embodiments where a silver halide layer as described is formed directly on the cellulose ester layer (one support, multi-layer element), best results are provided when the silver amount is 5-50 mg/l00 cm and the gelatin is present in an amount of l0-300 mg/cm These ranges are not limitative, but include commercially important silver halide systems per se.

The description on the use of the image receiving ma terials of the present invention has been mentioned hereinbefore, and the particularly preferred use is in a Polaroid-Land type camera. In this preferred case, the

image receiving material of the present invention is charged in the interior of a camera in the form of a sheet or roll, together with a silver halide light-sensitive material. As the case may be, the two materials may be charged in the camera in the form of a laminated sheet comprising several pairs of the two materials, or in the form of a long roll comprising a pair of the two materials, and the photographed part is drawn from the camera and cut with each picture taken. Upon the drawing of the photographed part, the two materials closely stick together in such a state that they are face to face with each other, a treating solution spread therebetween and the development carried out in this state.

The image receiving materials for a silver salt diffusion transfer process according to the present invention have various merits. For example, the images formed have high mechanical strength, and further these materials are extremely excellent for use in a Polaroid-Land type camera in that they may easily be drawn and cut and also easily rolled due to the good flexibility thereof.

If necessary, it is possible to optionally incorporate in the cellulose ester layer containing a fluorescent whitening agent(s) other additives such as a plasticizer, blueing dye, additive to prevent fadeing of a silver image (e.g., a compound having a mercapto group), toning agent, acidic compound which neutralizes an alkali, etc.

The present invention will now be illustrated in more detail by the examples given hereunder.

COMPARATIVE EXAMPLE 1 Preparation of support A solution consisting of the following components was superposedly applied twice in equal amounts on a base paper, drying after each application (base paper weight: g/m thickness: 0.125 mm), to make a film having a thickness of 10 p. after being dried.

Cellulose acetate (manufacturer: Daisel KK. acetylation degree: 55 i 0.5% trade name Cellulose acetate V-AC 20g C.l. Fluorescent Brightening Agent 91 (trade name: Kayalight B manufacturer: Nippon Kayaku KK) 045g Methanol 50 cc Methylene chloride 450 cc 2. Preparation of image receiving material The support obtained in (1) above was immersed in a hydrolyzing bath consisting of the following composition (solution temperature: 35 C) for 40 seconds, and then washed with flowing water for 4 minutes and dried.

Glycerin g Nickel nitrate (6 H O) 0.0l7 g Sodium sulfide (9 H O) 3.1 g Sodium hydroxide l20 g Methyl alcohol 720 cc Water 480 cc The thickness of the hydrolyzed layer was 2.5 a. (Acordingly, the cellulose acetate layer of a thickness of 7.5 a which was not hydrolyzed acts as a waterproofing layer). The measurement of the thickness was performed by dyeing the layer with a dyestuff (Sumilight Blue FBGC, manufacturer: Sumitomo Kagaku Kogyo KK) which dyes the hydrolyzed cellulose but does not dye the cellulose acetate and then observing a cross section thereof by means of a microscope. The Fluorescent Brightening Agent which was extracted in the hydrolyzing bath.

The amount of Kayalight B, was determined by means of the ultraviolet spectroabsorption method (carried out using a Cary Spectrophotometer Model 15). As a result thereof, it was confirmed that about 25% of the applied fluorescent whitening agent was extracted into the hydrolyzing bath.

The whiteness of the surface of the obtained image receiving material was very different from that of the coated support before hydrolysis, and in the state of the application of the cellulose acetate layer the whiteness of the image receiving material finally obtained could not be completely anticipated. When the hydrolysis treatment was continuously performed in the same hydrolyzing bath, the whiteness of the obtained image receiving material became uneven. Further, as a result of the accumulation of the fluorescent whitening agent, sludge precipitated.

3. Preparation of silver halide photo-sensitive material (negative element) To a support comprising a 20 ,u. thick polyethylene layer laminated on paper weighing lOO g/m a corona discharge was imparted to make the surface of the support hydrophilic, and then a gelatino silver bromoiodide photographic emulsion containing 5 mol "/t silver iodide was applied on the support. The amount of the emulsion which was coated on the support was 12 mg/lm calculated in terms of silver content in the emulsion, and 50 mg/lOOcm in terms of gelatin coated. A gelatin aqueous solution was superposed on the emulsion layer as a protective layer and then dried, the thickness of the gelatin protective layer being 0.5 a after being dried. 4. Treatment for development The silver halide photo-sensitive material, which had been imagewise exposed with an automatic exposure camera to daylight, and the image receiving material were superposed such that the activ layers faced each other, and then a treating solution consisting of the following ingredients was introduced between the two materials in a thickness of 100 a.

Diethyl hydroxylamine 1.6 g Zinc chloride 0.1 g Uracil 1.2 g Hydroxyethyl cellulose 0.72 g Potassium hydroxide 3.5 g 15 cc The thickness of the treating solution was maintained EXAMPLE 1 1. Preparation of support Onto a baryta coated paper (weight: l35 g/m", thickness of baryta layer: 25 a), a mixed solution consisting of the following composition was applied (Formation of A layer). The thickness of the coated layer was 5 ,u, after being dried.

Cellulose acetate (manufacturer: Daisel KK, acetylation degree: 605 i 0.5%; trade name (cellulose acetate T-AC") g Cl. Fluorescent Brightening Agent 91 (trade name: Kayalight B. manufacturer: Nippon Kayku KK) 0.45 g Methanol 50 cc Methylene chloride 450 cc The following solution was then applied on the dried coated layer resulting on the support (Formation of B layer). The thickness of the newly coated layer was 5 ,u, after being dried.

Cellulose acetate (manufacturer: Daisel KK, acetylation degree: 60.5 i 0.5%, same as above) 20 g Methanol cc Methylene chloride 450 cc 2. Preparation of image receiving material The support obtained in the above step (I was immersed in a hydrolysis-nuclei substance introducing bath consisting of the following materials for seconds at a temperature of 35 C, and then washed with a flowing water for 4 minutes and dried.

Glycerin I50 g Nickel nitrate (6 H O) 0.0l7 g Sodium sulfide (9 H O) 3.l g Sodium hydroxide I20 g Methyl alcohol 720 cc Water 480 Ct.

The thickness of the saponified layer was 2.5 a.

The amount of the Fluorescent Brightening Agent (Kayalight B) which was extracted in the hydrolyzing bath was about 1% of the total amount thereof which was initially present.

There was almost no difference between the whiteness of the image receiving material obtained and the whiteness before the hydrolysis treatment. Even after hydrolysis treatment was continuously conducted in the same hydrolyzing bath, no problems occured.

3. Formation of image and observations By using this image receiving material and the same negative material as was described in the Comparative Example, the same development treatment as in the Comparative Example 1 was carried out. A positive image having high reflection density was obtained on the image receiving material. Further, the white part of the non-image part had a high but even whiteness.

EXAMPLE 2 1. Preparation of support Solutions each consisting of the following components were used for the formation of the A layer and the B layer, and a support was prepared according to the same procedure as in Example I.

A layer Cellulose butyrate acetate (manufacturer: Eastman Kodak, U.S.A., trade name: Half Second Butyrate) 20 g Methanol 50 cc Methylene chloride 450 cc C.l. Fluorescent Brightening Agent 69 Leucopher DC (fluorescent whitening agent. manufactured by Sandoz A.G., Switzerland) 045 g B layer Cellulose butyrate acetate (same as in the A layer) 20 g Methanol 50 cc Methylene chloride 450 cc 2. Preparation of image receiving material The following solution was used as the hydrolysis (saponification) bath, and the same procedure was carried out as in Example 1 (the thickness of the saponified layer was 2.5 a).

-Continued Titanium white (trade name:

Glycerin 150 g Taipaque R820, manufacturer: lshihara L ad nitrat ()3 g Sangyo K K) (rutile-type, average Sodium sulfide (9 H O) 3.1 g a t cle size: 0.2- .5 u) g Sodium hydroxide 120 g lcthyl phthalate 10 g Methyl alcohol 720 cc Methanol 100 cc Water 480 cc Methylene chloride 900 cc Even after hydrolysis was continuously performed in the same hydrolyzing bath, no problems were encountered.

The negative material and the development treatment were the same as in Example I. A positive image of high reflection density was formed on the image receiving material, and the background had a high, even whiteness.

EXAMPLE 3 A polyethylene laminate paper which was formed by the following procedure was used instead of baryta paper, and the same procedure as in Example I was performed to prepare a support and an image receiving material on this polyethylene laminate paper.

On a base paper (weight: I g/m thickness: 0.125 mm), a low density polyethylene (Sumikasen L-402, manufactured by Sumitomo Kagaku Kogyo KK) containing 12% by weight of titanium white (Taipaque R- 820, manufactured by Ishihara Sangyo KK) was applied by extrusion, the thickness of the coated layer being 0.045 mm. The extrusion coating machine was provided with a screw type extrusion device (60 mm caliber) and a T-shape die of500 mm in width, and the coating speed was 30 min/min. The surface ofthe cooling roll used for casting was finished to be smooth. The surface of the coated polyethylene layer was subjected to discharge treatment by a corona discharge apparatus (by Repel High Frequency Laboratories Co., Ltd). The distance between electrodes was 8 mm and the discharge strength was 250 W.

Formation of image and observations The development treatment was performed as in Example l, and a positive image which has a high reflection density was formed on the image receiving material, the background having a high, even whiteness.

As compared with the supports of the earlier Examples, the support of Example 3 was superior with respect to surface brighteness. However, the adhesion between the polyethylene layer and the cellulose ester layer was somewhat weak in this example, and thus it was necessary to carefully perform the saponification treatment.

EXAMPLE 4 A plastic film which was prepared according to the following procedure was used instead of baryta paper, and the same procedures as in Example 1 were carried out to prepare a support and an image receiving material.

Preparation of plastic film The following mixed solution was prepared, and this was spread on a glass plate to form a film having a thickness of 150 p. after being dried.

Cellulose acetate (manufacturer: Daisel KK, acetylation degree: 60.5 $0.571) 100 g Formation of image and observations The same development treatment as in Example l was preformed, and a positive image having a high reflection density was formed on a background having a high, even whiteness.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is:

1. Image receiving materials for a silver salt diffusion transfer process which comprises at least two layers comprising a cellulose ester layer which contains at least one fluorescent whitening agent and a hydrolyzed cellulose ester layer which contains silver depositing nuclei, the said two layers being superposed.

2. Image receiving materials as claimed in claim 1 wherein said layers are superposed on a support, said hydrolyzed cellulose ester being on top of said cellulose ester which contains at least one fluorescent brightening agent.

3. Image receiving materials as claimed in claim 2 wherein said cellulose ester is cellulose acetate, cellulose butyrate acetate, cellulose propionate or a mixture thereof.

4. Image receiving materials as claimed in claim 2 wherein the support is a photographic base paper. a pigment coated paper, a polyethylene coated paper. a film of a high molecular weight substance or an artificial paper.

5. Image receiving materials as claimed in claim 4 wherein said pigment is baryta or titanium white.

6. Image receiving materials as claimed in claim 5 wherein said high molecular weight substance is polyethylene terephthalate, a cellulose ester, polycarbonate or polyvinyl chloride.

7. Image receiving materials as claimed in claim 1 wherein a heavy metal, a noble metal, or a sulfide, selenide or telluride of such a metal is used as the silver depositing nuclei.

8. Image receiving materials as claimed in claim 7 where the heavy metal is zinc, mercury, lead, cadmiun, iron, chromium, nickle, tin, cobalt or copper and the noble metal is palladium platinum, silver or gold.

9. Image receiving materials as claimed in claim 1 wherein the thickness of the hydrolyzed cellulose ester layer is from about 0.] a to about 20 ,u.

10. Image receiving materials as claimed in claim 9 wherein the thickness of the hydrolyzed cellulose ester layer is from 0.5 p. to 10 a.

11. Image receiving materials as claimed in claim 9 wherein the thickness of the cellulose ester layer containing fluorescent brightening agent is from about 0.5 ,u. to about 20 a.

12. Image receiving materials as claimed in claim 11 wherein the thickness of the hydrolyzed cellulose ester layer is from 1 to 10 [.L.

13. Image receiving materials as claimed in claim 11 wherein the fluorescent brightening agent is present in an amount of from about to 500 mg/m 14. Image receiving materials as claimed in claim 13 wherein the fluorescent brightening agent is present in an amount of from to 200 mg/m 15. A method for preparing image receiving materials comprising:

a. applying a cellulose ester layer containing at least one fluorescent whitening agent on a support;

b. forming a cellulose ester layer at least initially free of fluorescent whtening agent on said initial layer;

c. treating the surface of the thus coated support with a hydrolyzing bath and silver depositing nuclei to incorporate the nuclei in the hydrolyzed cellulose ester layer.

16. The method of claim 15 where said cellulose ester is cellulose acetate, cellulose butyrate acetate,

cellulose propionate or a mixture thereof.

17. The method of claim 16 where the thickness of the hydrolyzed cellulose ester layer is from about 0.1 p. to about 20 u.

18. The method of claim 17 where the thickness of the cellulose ester layer containing fluorescent bright- 'ening agent is from about 0.5 p. to about 20 p" ladium, platinum, silver or gold. 

1. IMAGE RECEIVING MATERIALS FOR A SILVER SALT DIFFUSION TRANSFER PROCESS WHICH COMPRISES AT LEAST TWO LAYERS COMPRISING A CELLULOSE ESTER LAYER WHICH CONTAINS AT LEAST ONE FLUORESCENT WHITENING AGENT AND A HYDROLYZED CELLULOSE ESTER LAYER WHICH CONTAINS SILVER DEPOSING NUCLEI, THE SAID TWO LAYERS BEING SUPERPOSED.
 2. Image receiving materials as claimed in claim 1 wherein said layers are superposed on a support, said hydrolyzed cellulose ester being on top of said cellulose ester which contains at least one fluorescent brightening agent.
 3. Image receiving materials as claimed in claim 2 wherein said cellulose ester is cellulose acetate, cellulose butyrate acetate, cellulose propionate or a mixture thereof.
 4. Image receiving materials as claimed in claim 2 wherein the support is a photographic base paper, a pigment coated paper, a polyethylene coated paper, a film of a high molecular weight substance or an artificial paper.
 5. Image receiving materials as claimed in claim 4 wherein said pigment is baryta or titanium white.
 6. Image receiving materials as claimed in claim 5 wherein said high molecular weight substance is polyethylene terephthalate, a cellulose ester, polycarbonate or polyvinyl chloride.
 7. Image receiving materials as claimed in claim 1 wherein a heavy metal, a noble metal, or a sulfide, selenide or telluride of such a metal is used as the silver depositing nuclei.
 8. Image receiving materials as claimed in claim 7 where the heavy metal is zinc, mercury, lead, cadmiun, iron, chromium, nickle, tin, cobalt or copper and the noble metal is palladium platinum, silver or gold.
 9. Image receiving materials as claimed in claim 1 wherein the thickness of the hydrolyzed cellulose ester layer is from about 0.1 Mu to about 20 Mu .
 10. Image receiving materials as claimed in claim 9 wherein the thickness of the hydrolyzed cellulose ester layer is from 0.5 Mu to 10 Mu .
 11. Image receiving materials as claimed in claim 9 wherein the thickness of the cellulose ester layer containing fluorescent brightening agent is from about 0.5 Mu to about 20 Mu .
 12. Image receiving materials as claimed in claim 11 wherein the thickness of the hydrolyzed cellulose ester layer is from 1 to 10 Mu .
 13. Image receiving materials as claimed in claim 11 wherein the fluorescent brightening agent is present in an amount of from about 5 to 500 mg/m2.
 14. Image receiving materials as claimed in claim 13 wherein the fluorescent brightening agent is present in an amount of from 10 to 200 mg/m2.
 15. A method for preparing image receiving materials comprising: a. applying a cellulose ester layer containing at least one fluorescent whitening agent on a support; b. forming a cellulose ester layer at least initially free of fluorescent whtening agent on said initial layer; c. treating the surface of the thus coated support with a hydrolyzing bath and silver depositing nuclei to incorporate the nuclei in the hydrolyzed cellulose ester layer.
 16. The method of claim 15 where said cellulose ester is cellulose acetate, cellulose butyrate acetate, cellulose propionate or a mixture thereof.
 17. The method of claim 16 where the thickness of the hydrolyzed cellulose ester layer is from about 0.1 Mu to about 20 Mu .
 18. The method of claim 17 where the thickness of the cellulose ester layer containing fluorescent brightening agent is from about 0.5 Mu to about 20 Mu .
 19. The method of claim 18 where the fluorescent brightening agent is present in an amount of from about 5 to about 500 mg/m2.
 20. The method of claim 19 where a heavy metal, a noble metal or a sulfide, selenide or telluride of such a metal is used as the silver depositing nuclei.
 21. The method of claim 20 where the heavy metal is zinc, mercury, leAd, cadminum, iron, chromium, nickel, tin, cobalt or copper and the noble metal is palladium, platinum, silver or gold. 